According to this model, speciation generally occurs uniformly, via the steady and gradual transformation of whole lineages

• In this view, speciation is seen as a smooth and continuous process (big changes result from many cumulative small changes)

• This view is supported by the fossil record of the horse, with many intermediate forms connecting the ancestral species to the modern equivalent

• The evolution of new species by gradual accumulation of small genetic changes over long periods of time

• Emphasizing slow and steady change in an organism 

• Occurs at a slow but constant rate 

• Over a short period of time it is hard to notice 

According to this model, species remain stable for long periods known as stasis when there is genetic equilibrium, before undergoing abrupt and rapid change (speciation) 

• In this view, speciation is seen as a periodic process (big changes occur suddenly, followed by long periods of no change)

• This view is supported by the general lack of transitional fossils for most species – however such absences could also be explained by the relatively rare and irregular conditions required for fossilization. 

• It is rare, rapid events of branching speciation 

• Characterized by long periods of virtual standstill ("equilibrium"), "punctuated" by episodes of very fast development of new forms